Concerns regarding the United States' vulnerability to a terrorist attack with smallpox have stimulated development of new vaccines, prophylactics and therapeutics. However, a new and successful smallpox vaccine intervention program, or one to treat exposed individual requires not only an effective vaccine, but also agents to treat the complications arising from a widespread vaccination program. Recently, we found that derG, an N terminal deamidated analogue of the human MHC II beta-chain (aa135-149) showed significant protective activity in infectious disease models of malaria and HSV and adjuvant activity for vaccines. The primary goals of this application are to determine the protective activity of derG for vaccinia infections, identify its mechanism of action to support its' development as an immunotherapeutic and/or prophylactic for vaccinia and smallpox infections as a single agent and as an adjuvant for vaccinia vaccines. The ultimate goal of these Phase I studies is to develop sufficient data to justify studies in a primate model of efficacy and animal safety and toxicology studies to support human clinical trials. In addition to the concern that smallpox may be used as a weapon of mass destruction, recombinant vaccinia viruses (VV) are also used as vaccines or as vectors for immunotherapy resulting in the recommendation that individuals working with VV vectors be vaccinated. However, the present vaccines, when available, are associated with serious complications in approximately 1:10,000 primary vaccinees, and mortality in about 1:10 6 primary vaccinations. Our strategy is to use derG as prophylaxsis and as an adjuvant for a replication incompetent vaccine prime to limit the toxicity by live vaccinia virus and to target mucosal activity. Thus, these studies will deliver derG and the vaccine by intranasal administration and will monitor both systemic and mucosal (pulmonary) immunity. We propose to use derG, together with an infectious, but replication incompetent VV (irradiated) vaccine to examine the hypothesis that immune augmentation with derG will prolong survival and also provide adjuvant activity for a replication incompetent vaccine, thereby providing an additional reduction in viral burden and prolongation of survival for vaccinia-infected mice as a model of smallpox infection. This hypothesis will be tested with the following Specific Aims: 1: Determine the immunoregulatory and adjuvant properties of derG during VV vaccination of mice. 2: Determine the immune augmenting and adjuvant activity of derG in mice sub-lethally infected with vaccinia as a model of smallpox. 3: Determine the therapeutic potential of immune intervention in the treatment of lethal vaccinia virus infections and identify surrogates of therapeutic activity. In these studies we will follow survival and ovarian viral titers after intranasal challenge with VV. The studies will also analyze the mechanism of action to identify immune surrogates for use in clinical studies.